The distance between the handle and the paddle of the bicycle makes a great difference to the riders' comfort. Different riders require different distances between the handle and the paddle. In order that the same bicycle can meet the comfort requirements of different riders, the handle of the bicycle is configured to be adjustable in front and back directions, so that, the distance between the handle and the paddle can be changed by adjusting the angle of the handle so as to meet the requirements of different riders. Folding bicycles have become very popular in the last twenty years, and it has become a very important requirement that the handle can be folded to minimize the bicycle.
FIG. 1 is a schematic view illustrating an adjusting mechanism for handle position of bicycle in the prior art. Middle part of the handle 1a is clamped tightly by the upper cover 2a and the lower cover 3a. The upper cover and the lower cover are hinged on one side with a hinge axle 4a. The lower cover and the handle vertical pipe 5a of the bicycle are fixed together. The draw-in bolt 8a goes through the upper cover, the lower cover and the handle vertical pipe, and is screwed into the inclined nut 9a at the bottom of the handle vertical pipe. By screwing the draw-in bolt, the handle vertical pipe and the inclined nut are tight-up and get stuck in the front fork vertical pipe, and the upper cover and the lower cover are made to clamp the handle tightly. When the draw-in bolt is released, the upper cover and the lower cover will release the handle. Now turn the handle and adjust its angle of inclination to meet the comfort requirements of bicycle riders. What's more, the handle can be rotated downwards for 180° and rotated leftwards and rightwards for 90°, so that the handle clings to the bicycle frame and the bicycle is partly folded. However, the folded handle has to be vertical to the front fork vertical pipe, which is by far unable to minimize the folded bicycle. Additionally, the locking of the upper cover and the lower cover and the locking of the handle vertical pipe and the inclined nut are realized by the same draw-in bolt, so when the draw-in bolt releases or locks the upper cover and the lower cover, the handle vertical pipe and the front fork vertical pipe will get released or locked accordingly. In order to ensure that the handle vertical pipe and the inclined nut are tight-up in the front fork vertical pipe reliably, the outer wall of the inclined nut is provided with vertical threads 15a which can increase the friction between the outer wall of the inclined nut and the inner wall of the front fork vertical pipe. The vertical threads will wear the inner wall of the front fork vertical pipe every time when the inclined nut is tight-up in the front fork vertical pipe. The inner wall of the front fork vertical pipe will be worn heavily after adjusting the angle of the handle for several times, which will affect the rigidity of the front fork vertical pipe, and thereby the safety performance of the bicycle. Additionally, since one bolt needs to release or lock two connections at one time, the bolt requires a long travel distance, which makes it impossible to replace the manual operation with common quick locking operation.
In recent twenty years, the vertical pipe joint of the handle of traditional folding bicycle is thus configured as shown in FIG. 7. The handle is provided with a vertical pipe extending downwards in the middle, and provided with a joint at the bottom. The joint is provided with an upper cover and a lower cover. The upper cover and the vertical pipe are closely linked together, and the lower cover and the front fork vertical pipe are closely linked together. The upper cover and the lower cover are hinged together on one side, and are provided with a cover locking mechanism on the opposite side, which can be operated easily without any tools. Thus the handle can be fixed for riding, also the handle can be released to fold the handle downwards for 180° so as to reduce the space occupied. This kind of folding method, which has been popular for about twenty-five years, is convenient, and the optimal position of the handle folded is chosen according to the angle of the hinge axle designed. However, this kind of bicycle has serious defects as follows: firstly, the front and back distance of the handle cannot be adjusted to meet the demands for riding; secondly, the machining accuracy required is too high, which causes unsatisfactory in the cost, the weight, the service life, and the safety. This method for folding the bicycle requires high intensity for the joint and high accuracy for the folding position, which makes the joint considerably heavy and the cost considerably high (30-50 RMB each). In order to minimize the space occupied by the bicycle folded, the angle of the brake handle of the bicycle is adjusted to around 0° (the angle to the horizontal plane), which doesn't meet the standard of the bicycle. And other mechanism must be added in order that the angle of the brake handle can be adjusted when folding the bicycle, which makes the operation inconvenient, the cost be increased by about 30 RMB and the weight increased by about 0.2 Kg.